It is broadly old to employ a spot of material (U.S. Pat. to Winter No. 3,597,054, 8-3-71) fluorescent to ultraviolet radiations to warn persons of the presence of dangerous intensities of such radiations. It is also known to utilize such materials in relatively complicated meters (McKee U.S. Pat. No. 3,194,963) and dosimeters (Jubb U.S. Pat. No. 3,710,115). But it is not known to provide a very simple device capable of being worn by a person to give a printed-message warning of the momentary presence of dangerous intensities of one, two or more ranges of such radiations. It is the principal object of this invention to provide such a device. Other objects and advantages will appear as the following description proceeds.